In a liquid crystal display device, liquid crystal is a substance that does not itself illuminate light. Instead, the liquid crystal relies on reflecting light from a light source, thereby displaying images and data. In the case of a typical liquid crystal display device, a backlight module powered by electricity supplies the needed light.
Typically, there are two types of backlight systems: an edge lighting type and a bottom-lighting type. The edge-lighting type of backlight system is widely used in small and medium size liquid crystal display for merits on its small weight, thin body and low energy cost. Large size liquid crystal display seldom uses the edge-lighting backlight system because the results based on the merits mentioned above is poor. Furthermore, the large size edge-lighting type backlight system seldom satisfies the requirement of light brightness and optical uniformity. Nowadays, the market demand for larger size liquid crystal display has increased progressively. Therefore, the bottom-lighting type of backlight system needs to be developed to satisfy the market demand.
Referring to FIG. 1, a typical bottom-lighting backlight module 10 is shown. The backlight module 10 includes a frame 11, a reflective plate 12, a diffusing plate 13, and a plurality of cold cathode fluorescent lamps 15. The frame 11 includes a flat substrate 112 and a number of circumferential sidewalls 114 extend from the substrate 112 to define an opening 116. The reflective plate 12 is disposed on the substrate 112 of the frame 11. The diffusing plate 13 is disposed on the opening 116 of the frame 11. The cold cathode fluorescent lamps 15 are positioned in the frame 11 under the diffusing plate 13. The diffusing plate 13 is used for uniformly diffusing the light emitted from the plurality of cold cathode fluorescent lamps 15.
However, in large sized backlight module, lengths of the cold cathode fluorescent lamps 15 are significantly long. Longer cold cathode fluorescent lamps 15 will distort at a higher range than its maximum flexibility causing it to break when subjected to vibrations from the liquid crystal display device. In addition, the sidewalls 114 of the frame 11 usually does not lend enough support to prevent the diffusing plate 13 from collapsing due to gravity, thus, the backlight module 10 may further includes a plurality of spacers disposed between the substrate 112 of the frame 11 and the diffusing plate 13, supporting the diffusing plate 13 and simultaneously clamping the cold cathode fluorescent lamps 15 to the reflective plate 12.
Referring to FIGS. 2 and 3, another typical bottom-lighting backlight module 30 is shown. The backlight module 30 includes a frame 31, a reflective plate 32, a diffusing plate 33, a plurality of cold cathode fluorescent lamps 35, and a plurality of spacers 20. The backlight module 30 is the same as the backlight module 10, except that the backlight module 30 further includes a predetermined amount of spacers 20 disposed between a substrate (not labeled) of the frame 31 and the diffusing plate 33. Each spacer 20 includes a flat base 22, a supporting column 24, two clamps 26, and two fasteners 28. The supporting column 24 is disposed on a middle portion of an upper surface of the flat base 22 for supporting the diffusing plate 33. The two clamps 26 are respectively disposed on two ends of the upper surface of the flat base 22 for fixing the two adjacent cold cathode fluorescent lamps 35. The fasteners 28 are disposed on two ends of the bottom surface of the flat base 22. The frame 31 and the reflective plate 32 respectively define a plurality of holes (not labeled) therein for receiving the fasteners 28. The spacers 20 are secured in the reflective plate 32 and in the substrate of the frame 31 by securing the fasteners 28 into the corresponding holes (not labeled) thereof.
However, the spacers 20 can be only used in backlight modules employing flat reflective plates, and such backlight modules has a lower optical uniformity.
What is needed, therefore, is a spacer, and backlight module using the same that overcome the above mentioned disadvantage.